Due to the characteristics of thin profile and low power consumption, liquid crystal displays (LCDs) are widely used in electronic products, such as portable personal computers, digital cameras, projectors, and the like. Generally, LCD panels are classified into transmissive, reflective, and transflective types. A transmissive LCD panel uses a back-light module as its light source. A reflective LCD panel uses ambient light as its light source. A transflective LCD panel makes use of both the back-light source and ambient light.
As known in the art, a color LCD panel 1 has a two-dimensional array of pixels 10, as shown in FIG. 1. Each of the pixels comprises a plurality of sub-pixels, usually in three primary colors of red (R), green (G) and blue (B). These RGB color components can be achieved by using respective color filters. FIG. 2 illustrates a plan view of the pixel structure in a conventional transflective liquid crystal panel, and FIGS. 3a and 3b are cross sectional views of the pixel structure. As shown in FIG. 2, a pixel can be divided into three sub-pixels 12R, 12G and 12B and each sub-pixel can be divided into a transmission area (TA) and a reflection area (RA). In the transmission area as shown in FIG. 3a, light from a back-light source enters the pixel area through a lower substrate 30, and goes through a liquid crystal layer, a color filter R and the upper substrate 20. In the reflection area, light encountering the reflection area goes through an upper substrate 20, the color filter R and the liquid crystal layer before it is reflected by a reflective layer 52. Alternatively, part of the reflective area is covered by a non-color filter (NCF), as shown in FIG. 3b. 
As known in the art, there are many more layers in each pixel for controlling the optical behavior of the liquid crystal layer. These layers may include a device layer 50 and one or two electrode layers. The device layer is typically disposed on the lower substrate and comprises gate lines 31, 32, data lines 21-24 (FIG. 2), transistors, and passivation layers (not shown).
In a single-gap transflective LCD, one of the major disadvantages is that, the transmissivity of the transmission area (the V-T curve) and the reflectivity in the reflection area (the V-R curve) do not reach their peak values in the same voltage range. As shown in FIG. 3c, the V-R curve is peaked at about 2.8v, while the “flat” section of the V-T curve is between 3.7 - 5v. The reflectivity experiences an inversion while the transmissivity is approaching its higher value.